In conventional mechanical seals, such as shown in U.S. Pat. No. 3,042,414, an elastomer U-cup or packing ring, as it is referred to in the patent, is received in a seat provided in one of the seal rings surrounding a shaft sleeve. A spring pressed expander ring expands the U-cup such that its outer surface conforms to its seat and also is in full contact with the shaft sleeve. Because of the springs, the U-cup must slide relative to the shaft sleeve and with full area contact, the frictional forces are quite high. The lip of the seal can also have a relatively sharp edge which can shear the elastomer U-cup and cause premature failure of the seal.